Indicator for internal combustion engines



Aug. 12,1941. G. w. BROWN INDICATOR FOR INTERNAL CQMBUSTION ENGINESFiled Dec. 14, 1939 g I I l I ll IND T I I l I l I l ll Patented Aug.12, 1941 INDICATOR FOR INTERNAL COMBUSTION ENGINES Gilman W. Brown,Danvers, Mass, assigncr of one-half to Charles H. Endee, Milton, Mass.

Application December 14, 1939, Serial No. 309,304

2 Claims.

This invention relates to indicators for internal combustion engines,especially high speed engines. These indicators form diagrams or graphsshowing the relation of the varying pressures in an engine cylinder tothe position of the piston in the cylinder. The efliciency of the enginemay then be readily determined from an analysis of these graphs.

Indicators of this type now known to the art are inefficient and fail torecord the pressures accurately, especially when forced to record atvery high speeds. This is largely due to excessive friction and errorscaused by inertia and momentum.

It is the object of this invention to provide an accurate indicatorcapable of responding instantly to changes of pressure and to providegreater precision in the diagram.

The invention will be best understood from the following description inconjunction with the accompanying drawing. It is to be understood thatthe invention is not limited to the details of construction andarrangement of parts illustrated in the drawing, since the invention asdefined by the claims hereinafter appended, may be otherwise embodiedwithout departure from the spirit and scope thereof.

It is also to be understood that the terms here used are for the purposeof description and not of limitation, and it is not intended to limitthe invention claimed herein beyond the requirements of the prior art.

In the drawing:

Fig. 1 is a view partly in longitudinal section of a device embodying myinvention.

Fig. 2 is a cross-sectional view on the line 2-2 of Fig. 1.

Fig. 3 is a view in cross section on the line 3-4 of Fig. 1.

Fig. 4 is a view in longitudinal section on the line 4-4 of Fig. 2.

Fig. 5 is a cross-sectional view on the line 5-5 of Fig. 1.

Fig. 6 is a View in cross section on the line 6-45 of Fig. l.

Fig. 7 is a diagrammatic view showing the relative position of the ventsand intake ports and the parts of the rotor and stator.

The device herein described may be considered as having three majorparts. There is a pressure responsive mechanism, a recording mechanism,and a coordinated drive mechanism. In the drawing, the pressureresponsive mechanism is generally denoted by the letter A, the recordingmechanism by the letter B, and the coordinated drive mechanism by theletter C. These various structures are positioned and supported by aframe generally denoted by the letter D. The pressure responsivemechanism A comprises a head portion E and a tube portion F.

The head portion E contains a stationary tube or hollow cylindricalstator I. A rotor or pressure responsive body 2 mounted in the stator Icomprises a small tube or hollow shaft 3 journalled in and extendingthrough the head E and the stator I and bearing two diametricallyopposite vanes t and 5 which extend radially from the tube 2 to theinner surface of the stator I. The stator I is also provided withdiametrically opposed partitions 6 and I extending from the innersurface thereof to the outer surface of the hub of the rotor 2. Thepartitions 6 and I divide the space within the stator into twosubstantially equal portions which are again divided, but notnecessarily equally, by the vanes of the rotor. Thus, when the rotor isin its normal or usual position before pressure is applied as shown inFigs. 2 and 3, vane 3 of the rotor is preferably quite near partition 6of the stator and consequently vane 5 of the rotor is quite nearpartition 'I of the stator. A gas inlet head 8 is secured to the headportion E as by cap screws 9. The head 8 is a disk-like membercompletely enclosing one end of the hollow cylindrical stator I, theother end of which is enclosed by the head portion E. The outer face ofthe head 8 is provided with a hollow projection having a substantiallysemicircular portion communicating with inlet ports I3 and I4 and alsohaving a threaded stem portion which is connected to a conduit II] (Fig.2). A valve II having a handle I2 is interposed in the conduit E8. Theother end of the conduit I0 is connected to the cylinder of an engine(not shown) in such manner that the gases in the cylinder are permittedto enter the conduit. Intake ports I3 and I4 in the inlet head 8 permitthe passage of gas in equal portions and under equal pressures from theconduit ID to the spaces between the adjacent vanes and partitions ofthe rotor and stator. These spaces should be quite small, and need beonly large enough to admit pressure to the vanes of the rotor. The rotoris stationary when pressure is first admitted; the movement of the rotoris, therefore, positively and precisely determined by the extent of thepressure. The slightest pressure admitted to the rotor at any time isinstantly effective. There are no large spaces which. allow the pressureto lag, accumulate or become dispersed. The rotor is instantlyresponsive because it is very light and is balanced during rotation. Theminimum of moving parts avoids friction and momentum. The spaces betweenparts 4 and 'l and between 5 and 6 are provided with vents l5 and itwhich insure the absence of back pressure against the vanes of the rotorduring movement under pressure, since these spaces are always subject toatmospheric pressure. An annular channel I? is formed in the headportion E and provided with an inlet 58 and an outlet IS. The head Ethus constitutes a water-jacket which permits cold water to becirculated about the rotor and stator to prevent overheating.

The tube portion F is provided with an inner tube 23 which is fixed inrelation to the head portion E, and an outer tube or sleeve 2i capale ofrotative movement about the tube 29. The

tube 3 of the rotor extends a short distance into the chamber formed bytube 20 and is there firmly secured to a flat spring 22 in such mannerthat relative rotation is not permitted. The flat spring 22 passesthrough a narrow slot 23 formed in the mid section of a sliding block24. Lugs 25 and 25 on the block 24 project into longitudinally extendinggrooves 21 and 28 formed in the walls of the inner tube 20 thuspreventing rotation of the block. Rotation of the tube 2 creates torsionin the spring 22, and the length of the spring subject to torsion isdetermined by the position of the sliding block 24; the nearer the blockapproaches the tube 3, the shorter the extent of the spring which may betwisted and the greater the resistance to rotation of the rotor. Alongitudinally extending aperture or slot 29 in the inner tube 25 givesaccess to the block 24 and permits it to be slid longitudinally of thespring. A longitudinally extending aperture or slot 3! is also formed inthe outer tube 2! thus permitting access to the slot in the tube 28 whentube 25 is rotated about tube 25 until the aperture in tube 2| is injuxtaposition with the aperture in tube 29. A scale 35 may be formed onthe outer tube 2| along the edge of the slot 3! to indicate theresistance of the spring for various positions of the block. Furtherrotation of tube 2% causes it to seal the opening 29 in tube 29. Anextension 32 forms an inlet for admitting cooling air or gas to thechamber formed by the tube 26. Cool air or gas thus admitted tends tokeep the spring 22 at an even temperature, and passes through tube 3 ofthe rotor thus cooling the rotor and adjacent parts and preventstransmission of heat to the recording mechanism. Ports 33 located in thetube 3 immediately beyond the inlet head 3 permit the escape of thesecooling gases and serve to insulate the extreme end of the tube 3 whichbecomes part of the recording mechanism B. A plug 67 in this extreme endof the tube 3 prevents the gases from entering the recording mechanism.

The recording mechanism B is provided with a tube 34 into which extendsthe rotor tube 3. A concave mirror 68 is located in the opposite end ofthe tube 34, and a source of light 35 is placed in front of the mirror.Light from this source passes through lenses and 31 which cause thelight beams to converge on a concave mirror 38 mounted on the end of thetube 3. The light beams so reflected pass through a hood 39 to a lightsensitive film 48 held by a support 4! slidably mounted in a portion ofthe frame D. A shield 45a protects the film when not in use.

The drive mechanism C is designed to give the film support 4! a limitedreciprocating movement in timed relation to the movement of a piston(not shown) of the engine being tested in order to obtain a properdiagram. In this drive mechanism, a disc crank 42 is driven at engineshaft speed by the engine being tested, and transmits a reciprocatingmotion to support 41 through a telescoping connecting rod whichcomprises a rod 43 and sleeve 44 capable of relative movement when norecording is being made. An eccentric of the same throw may be used inplace of the crank, if preferred. The sleeve 44 is provided with springs45 and 46 having teeth 47 and 43. The sleeve 44 is also provided with acam sleeve or ring 49 having cam surfaces and 5! (see Fig. 6). The camring 49 also has a projecting arm 52 adapted to engage a cam bar 53pivotally mounted on a portion of the frame D. The cam bar or throw-outbar 53 is normally held in operative position by a spring 5%. A lateralextension of this bar forms a handle 55. When the cam bar is inoperative position as shown in Figs. 1 and 6, the arm 52 is deflected,thereby rotating the cam ring and causing the cam surfaces 50 and 5! tospread the springs 45 and 45, thus preventing teeth 41 and 48 fromengaging the rod 43. When the handle 55 is depressed, allowing the arm52 and cam ring 45 to assume the position shown in dotted lines in Fig.6 under the impulse of a spring 56, in which the cam surfaces 59 and Elno longer engage springs 45 and 4E. Thereupon teeth 41 and 45 dropthrough apertures 51 and 58 in the sleeve 44 and come to rest in notches59 and 6D in rod 43, thus locking the rod 43 and sleeve 44 and causingthe rotative movement of the disc crank 42 to be transmitted as areciprocative movement of the film support 4|. A vent 6| in the sleeve44 prevents back pressure against the rod 43. The rod 43 and sleeve 44will remain locked together and reciprocation of the support 41 willcontinue only while the handle 55 is depressed. When the handle 55 isreleased, the cams 53 and 5! will engage the springs and 45 at the endof the stroke and release the connection between the rod 43 and sleeve44.

In operation, gas from the engine cylinder under examination is admittedto the conduit Hi. When the valve II is opened, the pressure of the gasin the cylinder is transmitted equally through the two-port inlet head 8to corresponding surfaces of the opposite rotor vanes, causing a slightrotative movement of the rotor. There is no back pressure or increasedresistance to this movement, since the spaces into which the vanes moveare subject to atmospheric pressure because of the presence of vents l5and 16. Since both vanes of the rotor and opposite sides of the rotorbody are subjected to equal pressures, the body of the rotor is held inbalance, and there is no pressure or weight on the journals to causefriction, so that the rotor is substantially balanced during operation,and inertia and momentum are not allowed to interfere with the accuracyof the diagrams.

When it is said that equal pressures are applied to opposite sides ofthe rotor, this means that pressures derived from the engine cylinderare introduced equally into the chamber defined by vane 4 and partition6 and the chamber defined by vane 5 and partition 1.

The movement of the rotor is resisted by the is pressed downwardly thebar 53' fiat steel spring 22 firmly fixed to one end of the tube 3, andthe degree of resistance is determined by the position of the slidingblock 24. The concave mirror 38 on the other end of the tube 3 reflectsconcentrated beams of light from the lamp 35 to the light sensitive film46, and also serves to further concentrate the beams. When the film isreciprocated horizontally at engine shaft speed the variation incylinder pressure is transmitted as a variation in rot'ative movement ofthe rotor and as a variation in the position of the light beam in aplane perpendicular to the horizontal plane in which the film moves.Since the film is moved in timed relation to the piston of the engine, agraph is v.

formed on the film which shows the relation of pressure to pistonposition, from which the ciliciency is determined.

I claim:

1. An apparatus for indicating and recording the gas pressure in anengine during operation having a record sheet, means for moving therecord sheet in timed relation to the movement of the engine piston,pressure responsive means, and means for producing a representation onsaid record sheet of the movement of said pressure responsive means,said apparatus being characterized by pressure responsive means having acasing providing a cylinder, a rotor within said cylinder having itsaxle rotatably mounted in said casing, a straight flat spring secured atone end to said axle and projecting axially therefrom, and means mountedfor adjustment lengthwise of said spring and adapted to hold the latterrigid at a position spaced from said axle.

2. An apparatus for indicating and recording the gas pressure in anengine during operation having a record sheet, means for moving therecord sheet in timed relation to the movement of the engine piston,pressure responsive means, and means for producing a representation onsaid record sheet of the movement of said pressure responsive means,said apparatus being characterized by pressure responsive means having acasing providing a cylinder, a tube mounted for rotation in said casingand extending through said cylinder and easing with its axis alignedwith the ads of said cylinder, a rotor within said cylinder carried bysaid tube, a straight fiat spring secured at one end to said tube andprojecting axially thereof, means mounted for adjustment lengthwise ofsaid spring and adapted to hold the latter rigid at a position spacedfrom said tube.

GILMAN W. BROWN.

